Getting information about an error

[Lennart Borgman (gmail)]

I am trying to get information about an error that happens during 
fontification. I have something like this

      (condition-case err
          (funcall major)
        (error
         (mumamo-display-error 'mumamo-funcall-major "%s: %s"
                               major
                               (error-message-string err)))))

This writes the error to a log buffer, but I only get the name of the 
error (which is "Wrong type argument: stringp, nil"). I would need a 
traceback from inside that (funcall major). Is there a way to get that?